Figure 3.
Both Golgi localization and PtdIns4P phosphatase activity of Sac1 were key for its function in autophagy. (A) Schematic representation of yeast Sac1 and indicated truncates checked for function in autophagy. (B and C) Sac1 mutants with catalytic domain truncated or with localization domain truncated could not restore autophagy and cell resistance to nitrogen starvation in sac1∆ cells. (D and E) Sac1 mutants with a point mutation in catalytic domain lost the ability to restore autophagy and cell resistance to nitrogen starvation in sac1∆ cells. (F) PtdIns4P level is increased in sac1∆ cells detected by PtdIns4P-specific probe GFP-PHPLEKHA3. Scale bars: 5 μm. (G) Sac1 was tagged with GFP and its co-localization with ER marker Sec61 and Golgi marker Vrg4 was detected before and after starvation. (H and I) Localization of differently truncated Sac1 was observed before and after nitrogen starvation. Scale bars: 5 μm